In most cases the key of each piece given a TWV number is shown by the alphabetical letter following the colon, thus:TWV 55:a3 means that it is the third piece in A minor in the group of pieces numbered TWV 55. Lower case letter=minor key; upper case=major. Therefore it is superfluous to add to the title what key a piece is in, unless the TWV number is unknown or does not contain a key letter. Also, as it is a German system, it means that B=B-flat, b=B-flat minor, H=B major, h=B minor.